Found A/C clutch hub damage. Got one - junk yard. Slips Both when A/C on & off on 2000 Ford Taurus

I re-used same initial air gap spacer. Clutch turns very slowly when A/C on (not at all same speed as pulley) and very very slowly when off--but should not turn at all--should it? Not sure if air gap, bad coil, relay, or what.
Serpentine belt replaced year ago by dealer. A/C was working great till it just stopped a week ago and I noticed damaged clutch hub and a bit of clanging as it spun slowly. I took hub off. Pulley bearing grease cover was loosened by the failed hub and came off. No unusual other noises after hub removed--but am worried about bearing exposure to elements.
But not clear why clutch will not engage and fully dis-engage. Is gap too small? Should I be able to manually spin hub when A/C is off? Quite hard. I measured depth of bore in both hubs and they were within .004" of each other. I did not check coil resistance or anything else.
Ideas?
RC

Junkyard compressor/parts is likely problem. I would never use one of those. You likely have a compressor locking up. Get a new or reman assembly and make sure you replace receiver drier and expansion valve and flush out the condensor because of the very good chance of black death blockage in the condensor. You may have to replace condensor if cannot get good flow thru it.

Thanks for reply. The car is not in that great shape. With all these added expenses, not sure it is a good idea to repair--may need to replace. I was hoping for lower cost solution.
Basic question is what causes the clutch to rotate so slowly? No bearing noises. Am getting some cooling even with clutch running slowly (slipping)--but I do not let it slip, as that heats things up.
RC

Would need to know the gauge readings. Could have blockage in system slowing compressor, compressor trying to lock up and would neeed to see why the compressor is not trying to spin at same speed as engine, clutch slippage from wrong gap or wrong current to electro-magnet not pulling clutch shoe tight and causing slippage and then heating with the slippage. Gobs of things that could be.
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Yes the coil is definitely degraded because it should have been replaced when did original repair attempt. If the engine is turning the pulley at idle and the clutch is turning slow then it is either not engaged against the front of pulley and is slipping or the coil is failing or bad or has power prob to it. If the clutch is sucked against the pulley when turning it will turn compressor unless locking/locked and belt will squeal loudly pulling thru pulley.

I will check voltage to coil. And coil resistance. When I say clutch is rotating slowly (with A/C on) I mean about one rev/sec or 60 RPM. Zero RPM with A/C off. So, no good way to measure the pressures, as the compressor is not at pulley speed. I can measure system pressure at zero RPM. Will not tell us much.
Maybe the electrical info will give a hint. It is possible that the coil is degraded due to the prior heat generated by the slipping clutch.
RC
I checked the static pressure (engine off) and gauge read 80 psi. I then turned on A/C (with bad clutch slip) and pressure dropped to 65 psi. So--not a valid test. I then swapped A/C clutch relay with one next to it with same part number. No change.
Any ideas on how to feed 12VDC to the coil? It is buried on the Duratec and I cannot reach it. Is there an intermediate connector that is more accessible?
RC